S-ethyl thioacetate

Mukaiyama et al. have shown that a BINOL-derived oxotitanium catalyzes the asymmetric aldol reaction of aldehydes with thioester silyl enolates [147]. In the presence of the chiral complex (20mol%), the TBS enolate of S-t-butyl thioacetate reacts smoothly with aromatic and a,/ -unsaturated aldehydes in toluene to give silylated aldols in high yields with moderate to good enantioselectivity (91-98%, 36-85% ee). The use of the TBS enolate of S-ethyl thioacetate results in lower enantioselectivity. 

S-methyl thioacetate (MTA) (1534-08-3), S-ethyl thioacetate (ETA) (625-60-5), dimethyl disulfide (DMDS) (624-92-0), diethyl disulfide (DEDS) (110-81-6), carbon disulfide (CS2) (75-15-0), dimethyl tiisulfide (DMTS) (3658-80-8), 2-mercaptoethanol (ME) (60-24-2), 2-(methylthio)-l-ethanol (MTE) (5271-38-5), 3-(methythio)-l-propanol (MTP) (505-10-2) and 4-(methylthio)-l-butanol (MTB) (20582-89-3). 2f Dimethyl sulfide (926-09-0), isopropyl disulfide (4523-89-8) and 3-(methylthio)-l-hexanol (51755-66-9) were used as internal standards. The commercial standards were purchased from either Sigma-Aldrich (Auckland, New Zealand) or Alfa Aesa (Ward Hill, MA, USA). A methanethiol gas cylinder was supplied by Matheson Coleman and Bell (East Rutherford, NJ, USA). The standards were used to identify peaks in the chromatograms and to construct calibration curves for quantification pnuposes. 

Ha-Dimethyl sulfide was used to quantify methanethiol, ethanethiol, dimethyl sulfide, diethyl sulfide, methyl thioacetate, S-ethyl thioacetate. Isopropyl disulfide was used for dimethyl disulfide, diethyldisulfide, carbon disulfide, dimethyl trisulfide. Other compoxmds including 2-mercaptoethanol, 2-(methylthio)-l-ethanol, 3-(methythio)-l-prop)anol and 4 (methylthio)-l-butanol were quantified using 3-(methylthio)-l-hexanol as the internal standard. 

---